Sample size (or number of clusters) by treatment arms
Four treatment conditions (2×2 factorial design):
Treatment 1 (One suggestion, No explanation): 60-80 participants (12-16 sessions)
Treatment 2 (One suggestion, With explanation): 60-80 participants (12-16 sessions)
Treatment 3 (Two suggestions, No explanation): 60-80 participants (12-16 sessions)
Treatment 4 (Two suggestions, With explanation): 60-80 participants (12-16 sessions)